not always firing on #1

[john h]

Hey all,

I'm new to the board.  So far I've seen a lot of good info, so I'm glad I found it. I';m sorry for writing so much below, but I want to give as much info as possible.   I have a 73 Cuda with a crate 360 motor.  I have a Edelbrock AVS 650 carb on it.  I have been fighting with this carb for a number of years.   there are a couple of issues issues I have been having I assumed were carb issues.  I have been chasing a lean Surge issue when coming off a cruise at say 40 and trying to lightly accelerate to 50. same with any constant speed to a light acceleration.  It would surge and then level out and cruise just fine.  I have the carb kit with the different springs and metering rods and jets.  I have been working through different combos.  I can get it close but not perfect.  IF I get it to idol nicely, I have surging when accelerating if I get the surge to go away I have poor idol quality.  it seems I'm working with at least a couple of different issues. It seems to have a miss at around 2500-3000 in park standing behind the car listening not sure about under load as I can't hear it. I have the initial  timing set at 12 Deg BTDC no advance hooked up while setting timing.  I have it jetted as factory settings and I have the stiffest rod spring in because I have tons of vacuum.  It will stumble out of the hole.  so I adjust the the mixture screws a bit richer and adjust the squirt on the pump to fix that and then the idol quality goes to hell.  I bought a vacuum guage to help me fine tune this thing.  The needle is not steady at all, but only fluctuates less than 1 HG just does not sit completely still. the guage said timing was not quite right, so I advanced it a bit more not sure how much because I run out of marks at 12 and don't have a dial back timing light.  I then get about 19hg at idol and the engine seems to like that timing sligltly higher than 12.  the guage is still not steady, but better Possibly this is due to valve overlap? the  vacuum guage reads 19 for a while and then blip it drops off to about 18 and back up to 20 for a little while, settles back at 19. once I noticed this on the guage, I started to be able to hear/see it in the exhaust and the tremor in the motor.  I put the timing light back on and realized the strobe was slow at times and other times it was not turning on right away.  I tried a few other plug wires just to test the strobe and they were fine.  I started thinking my 2nd issue is it's not always firing on #1  I pulled the plugs on the even side and they seem a little lean.  I pulled the plugs on the odd side and #1 is not fowled, but much more dark than the rest of the pugs on that side. I pulled the cap and it looks good, it was replaced last summer.  the rotor looks good no corrosion.  when running I pull the #1 plug from the cap and it really does not change the idol a great amount but neither do any of the cylinders when I pull them from the cap.  I replaced the plug wire and plug.  I still have the same issue.  the exhaust on that side sort of makes a putting sound.  I have not run it enough to since replacing the plug and wire  to see a big color difference yet.  Should I be thinking I have bad compression in that #1 cylinder?  is this a carb issue? if it was a cab float or leak would it affect that entire bank of cylinders?  where do I go from here?

Thanks in advance for any advice.
John

[Chryco Psycho]

Welcome 
To me it sounds like a float level problem , I think 7/16 is normal , try raising to 3/8" , the other thing to look at is an instant pump shot from the squirter even with slight movement , there has to be a ball brg under the squirter to prevent back flow
Next lose the vacuum advance most engines run better without it you should about 16* at idle & 36 total this way .
 You may have a intake gasket leak pulling oil from under the intake , check to be suree all the intake bolts are tight , you do not have a brake booster or PCV plugged into #1 runner do you , not even sure what intake you are using ?

[72cudamaan]

Might be a good idea to pull the dist. cap and look for worn contacts.

[cudabob496]

well, my first though was to get a Holley, but, I'm prejudiced.
Second thought is to make sure all other normal things you would check
for on a regular tuneup are okay. Good plug wires, distributor cap good, etc.
But a bad float or float level could certainly contribute to a lot of the things you
are seeing.

[john h]

Welcome 
To me it sounds like a float level problem , I think 7/16 is normal , try raising to 3/8" , the other thing to look at is an instant pump shot from the squirter even with slight movement , there has to be a ball brg under the squirter to prevent back flow
Next lose the vacuum advance most engines run better without it you should about 16* at idle & 36 total this way .
 You may have a intake gasket leak pulling oil from under the intake , check to be suree all the intake bolts are tight , you do not have a brake booster or PCV plugged into #1 runner do you , not even sure what intake you are using ?

brake booster is plugged into a port on the back of the Intake.  The intake is a Dual plane stock intake to the Magnum 360.  the PCV is connected to the port on the front of the carb.  If I was having a float issue, wouldn't it affect all the cylinders on the left side rather than just the #1 Cylinder? I forgot to mention that I don't have a torque wrench, but I did put a 3/8" drive socket and all teh bolts on the intake seemed a bit loose to me but all about the same tightness.  I snugged them just a bit more in the pattern shown in the book.  It did not change the issue. I suppose it's possible that the gasket is shot and no tightening will fix it.  I will pull the carb and check the float level with the drill bit trick.

[Chryco Psycho]

I rarely use a torque wrench as you cannopt get on most of the bolts abyway but it is good practice to use a wrench & make sure the bolts are snug , the low float level will cause the stuble but not the rich condition for #1 plug

[Bullitt-]

Just read an article in the April HRM about a 360 in a Dart that was having issues after converting to an MSD ready to run distributor/blaster coil , hard to start was primary but even when that was resolved there was an intermittent miss. They were reading less than 12V at the coil that dropped as the car warmed up. Seems all the issues were traced to electrical supply, poor connections, bad voltage regulator, bulkhead connector.
 The final fix was to run power for the ignition through a relay straight from the battery activated by the original start/run wires. 

[john h]

Just read an article in the April HRM about a 360 in a Dart that was having issues after converting to an MSD ready to run distributor/blaster coil , hard to start was primary but even when that was resolved there was an intermittent miss. They were reading less than 12V at the coil that dropped as the car warmed up. Seems all the issues were traced to electrical supply, poor connections, bad voltage regulator, bulkhead connector.
 The final fix was to run power for the ignition through a relay straight from the battery activated by the original start/run wires.

That is interesting.  I have owned the car for 25 years and ever since I owned it, the lights would dim significantly when rolling to a stop light. the Meter will show neutral and at times even discharge if it sits there in gear idoling with the lights on too long.  I have replaced the voltage regulator, the coil (blaster brand) and the ignition control box.  I'm have a new engine wire harness and have checked my grounds many times. 

I appreciate all the advice.  I'm keeping a log so I can try everything out and mark it off the list.

John

[moparmaniac59]

It could be something as simple as a split plug boot or bad wire. How old are your wires? I've had this issue before and it was just that...a bad plug wire. I has a very small split in the plug boot & it would arc to the block (intermittantly) and cause a mis-fire issue. One way to check for a cylinder not firing is to use a laser heat temp sensor pointer. Those things are great, you can buy one at Harbor Freight for about $30 bucks. Just point the laser at each of the cylinders and check the temperature readout. A cooler reading on one cylinder may indicate a mis-fire. And sometimes a split wire/boot isn't initally visible until it's pulled off and inspected closer. Hope you get it figured out!! 


                                                                         Matt B.

[john h]

It could be something as simple as a split plug boot or bad wire. How old are your wires? I've had this issue before and it was just that...a bad plug wire. I has a very small split in the plug boot & it would arc to the block (intermittantly) and cause a mis-fire issue. One way to check for a cylinder not firing is to use a laser heat temp sensor pointer. Those things are great, you can buy one at Harbor Freight for about $30 bucks. Just point the laser at each of the cylinders and check the temperature readout. A cooler reading on one cylinder may indicate a mis-fire. And sometimes a split wire/boot isn't initally visible until it's pulled off and inspected closer. Hope you get it figured out!! 


                                                                         Matt B.

the plug wires have about 300 miles on them.  just to be sure I replaced the #1 cylinder plug with an old on I kept laying around after the new wires were put on.  No change. with either wire.  I like the idea of the heat pointer.  I know where I can borrow one from.

John

[Chryco Psycho]

the Alt doesn't turn fast enough to keep up the power at idle normally ,  the only fix is to go to a modern Denso unit

[cudabob496]

the Alt doesn't turn fast enough to keep up the power at idle normally ,  the only fix is to go to a modern Denso unit

440 Source told me PowerMasters were much better?

[Chryco Psycho]

I had a Powermaster last 3 days once
 I will take a Denso production unit thanks

[cudabob496]

I had a Powermaster last 3 days once
 I will take a Denso production unit thanks

ya, nothing guaranteed, but 440sourse sure seemed to like powermaster!
Put one one a year ago and 14.5 volts all day long

[cudabob496]

could check ohm resistance on your #1 plug wire, to see if you have an open?